Development of Electromagnetic Wave Absorbers Having the Ultra Wide Bandwidth Absorbing Center Frequency

超宽带宽吸收中心频率电磁波吸收体的研制

基本信息

批准号：
14550309
负责人：
YOSHIKADO Shinzo
金额：
$ 1.66万
依托单位：
DOSHISHA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

We developed conductor-backed single layered electromagnetic wave absorbers made of ferrite composites (spinel-type Ni-Zn ferrite, SiO_2) having the ultra wide bandwidth absorbing center fFrequency. The density and the hardness are improved by adding B_2O_3, but the conductance value increases with increasing the density. It degrades the absorption characteristics of a metal-backed single layered electromagnetic wave absorber in the high-frequency region. The conductivity was reduced by adding oxides such as CoO, NiO or MnCO_3. The complex permeability, however, decreased for the ferrite composites with added CoO or NiO but did not change for that with added MnCO_3. Composite electromagnetic wave absorbers fabricated by adding B2O_3 and NiO or MnCO_3 operated in the frequency region up to 6 GHz without decreasing both the density and the hardness. The ferrite composite with added B_2O_3 and MnCO_3 had a wide selection range of the absorbing center frequency by simply changing the thick … More ness while maintaining the absorption characteristics.Electromagnetic wave absorbers coated with ITO thin film with the required center absorbing frequency can be made by choosing the suitable thicknesses of both the film and the ferrite composite without changing the composition of the absorber. Absorbing characteristic of electromagnetic wave absorbers added CoO or NiO having required center absorbing frequency below approximately 5GHz can be achieved by coating of ITO thin film with the suitable thicknesses or resistivity without changing the composition.The absorption characteristics of ferrite composites using fine powders of SiO_2 with the average grain size of approximately 30 nm, 12 nm or 7 nm were improved compared with those of ferrite composites using SiO_2 powders of the average grain size of approximately 29 mm in the low frequency region below 1 GHz. Furthermore, grain size dependence of ferrite composites of fine powders of Ni-Zn ferrite (20 mol%) and SiO_2 (80 mol%) with the normal size such as 29 mm was investigated by the simulation using the model. Result of simulation shows that electromagnetic waves above 90 % in the wide frequency region similar so Ni-Zn ferrite is absorbed in the low frequency region below 1 GHz and is absorbed in the high frequency region above 1 GHz by changing the thicknesses of the absorbers. Less

我们开发了由铁氧体组合物（尖晶石型Ni-Zn铁氧体，siO_2）制成的导体支持的单层电磁波吸收器，具有超宽带宽吸收中心的Ffquermenty。通过添加B_2O_3来提高密度和硬度，但是电导值随着密度的增加而增加。它降低了高频区域中金属支持的单层电磁波吸收器的吸收特性。但是，对于添加的COO或NIO的铁氧体组成，复合物的渗透率降低了，但随着添加的MNCO_3没有改变。通过添加B2O_3和NIO或MNCO_3制造的复合电磁波吸收器在频率区域中运行，最高6 GHz，而不会降低密度和硬度。具有添加B_2O_3和MNCO_3的铁氧体复合材料通过简单地改变厚度……在保持吸收特性的同时，可以通过选择薄膜和所需的中心频率来使胶片和更改ferrite ferrite的厚度来更改ferterite的厚度，从而使iTo薄膜涂有薄膜涂有薄膜，从而使吸收性波吸收器具有更为重要的同时。电磁波吸收剂的吸收特征添加了所需的中心吸收频率低于5GHz，可以通过涂层ITO薄膜涂层，具有合适的厚度或阻力，而无需更改组成的苦难特征。使用SIO_2的精细粉末与平均晶粒尺寸相比，这些较高的粉末量与这些成分的平均成分相比，该材料的平均成分是12 nm，12 nm，12 nm，12 nm，12 nm，12 nm，12 nm nm，在1 GHz以下的低频区域中，平均晶粒尺寸约为29毫米的SIO_2粉末。此外，使用模型研究了使用模型的模拟研究了Ni-Zn铁氧体（20 mol％）和SIO_2（80 mol％）的细粉的铁素体组成（20 mol％）和SIO_2（80 mol％）的晶粒大小依赖性。模拟的结果表明，在宽频率区域中，电子波超过90％，因此Ni-Zn铁氧体在1 GHz以下的低频区域中被吸收，并通过改变吸收剂的厚度在1 GHz以上的高频区域中吸收。较少的